Sheet feed deflector and interrupter responsive to photoelectric sheet position sensing means



March 21, 1967 P. FOIAS ETAL. 333G304 I SHUT FEED DEFLECTOR ANDINTERRUPTER RESPONSIVE TO PHOTOELECTRIC SHEE'I POSITION SENSING MEANSFiled Feb. 28, 1966 2 Sheets-Sheet l IN ENTORSI PA VEL Poms GHEORGHE EWACHE BY DAV/D BEfiGMA/V ATTORNEY.

March 21, 1967 P. FOIAS ETAL SHUT FEED DEFLECTOR AND INTERRUPTERRESPONSIVE TO PHOTOELECTRIC SHEET POSITION SENSING MEANS 2 Sheets-Sheet2 Filed Feb. 28, 1966 IIIIH INVENTORSI PA VE' L F OIA 5 GHEORGHE E/VACHE DA V/D BERG/WAN United States Patent SHEET FEED DEFLECTOR ANDINTERRUPTER RESPONSIVE T0 PHOTOELECTRIC SHEET POSI- TION SENSING MEANSPavel Foias, Gheorghe Enache, and David Bergman, Bucharest, Rumania,assignors to Comitetnl de Stat Pentru Cnltura si Arta, Bucharest,Rumania, a corporation of Rumania Filed Feb. 28, 1966, Ser. No. 530,6265 Claims. (Cl. 27157) This application is a continuation-in-part of ourcopending application Ser. No. 351,145, now abandoned, filed Mar. 11,1964.

Our present invention relates to a sorting device for a printing plant,designed to determine by photoelectric means the correct feeding of asuccession of single sheets of paper to a printing cylinder and todeviate improperly positioned and/or superposed sheets from their normalpath.

In a printing plant it is customary to feed the blank sheetstangentially to the printing cylinder, carrying the usual form on itsperiphery, and to urge the sheet against the rotating form with the aidof a counterpressure roller, the form being concurrently brushed by aninking roller or the like ahead of its point of contact with the sheet.

Photoelectric systems adapted to divert improperly positioned (e.g.oblique or overlapping) sheets are known per se. If such systems areplaced in the feed path of a printing cylinder along with the sheets,normally advance in timed relationship with the rotation of thecylinder, deviation of one or more sheets from their path would normallycause the cylinder to perform a corresponding number of revolutionswithout interposition of a paper layer between the form and thecounterpressure roller. This,

that the latter would smudge the rear surface of the next 'sheetdelivered to the cylinder.

An object .of our invention, therefore, is the provision of means forpreventing such smudging without the need for stopping the printingcylinder upon a diversion of an improperly placed sheet, thus enablingcontinuous operation of the printing press.

This object is realized, in accordance with our invention, by theprovision of photoelectric detector means which, in a manner known perse, produce a defect signal in response to improper positioning of anoncoming sheet, in combination with electromagnetic release meanscontrolled thereby to disengage the pressure roller from the printingcylinder upon the occurrence of such signal, the operation of therelease means coinciding with that of a sorter whose sheet-deflectingposition is maintained for the remainder of an operating cycle of theprinting press, i.e. to the end of the cylinder revolution then inprogress.

The photoelectric detector means advantageously includes a combinationof photocells designed in part to scan the edges of oncoming sheets, forthe purpose of ascertaining any oblique positioning thereof withreference to the direction of advance along the guide path, and in partto sense the occurrence of sheet duplications, the two cell assembliesbeing connected in parallel to the input of an associated controlcircuit whose output includes suitable electromagnetic devices, such assolenoids, for operating the sheet deflector and the release mechanismfor the pressure roller. A timer, such as a set of cams mechanicallycoupled with the driven printing cylinder, insures the maintenance ofthe operative condition of these electromagnetic devices for theduration of a cylinder revolution. This timer may also be used,according to another feature of our invention, for the purpose ofdisabling the photoelectric detectors-especially the edgeice scanningcells thereofduring part of a cycle so that the test of correctalignment of a sheet with its guide path will be made only at specifiedintervals to avoid the generation of false defect signals.

The invention will be described in greater detail with reference to theaccompanying drawing in which:

FIG. 1 is a perspective view of a portion of a printing press, includinga set of supervisory photocells disposed along a guide path for papersheets to be successively fed to a printing cylinder: and

FIG. 2 is an overall circuit diagram of the system shown partly in FIG.1.

As illustrated in FIG. 1, there is provided a guide path for asuccession of sheets 30, this guide path including the base plate 40bounded by rails 31 between which the sheets are advanced by suitablefeed means such as one or more pairs of transport rollers (not shown). Aphotoelectric detector 1, disposed midway along the width of the plate40, senses the simultaneous passage of two or more superposed sheetsWhile two other detectors 2 and 3, flanking detector 1, determine theparallelism of an oncoming sheet 30 with reference to the rails 31. At alocation just beyond the detector assemblies 1-3, a set of rocker arms16 are swingably mounted on a common shaft 15. The plate 40 terminatesahead of the region of the arms 16 so that the latter can swing withtheir rearwardly pointing ends below the level of that plate to pick upthe leading edge of any sheet to be deviated from its normal path oftravel toward a printing cylinder. In the absence of a defect signalfrom any of the photocells 1-3, however, the tips of the arms 16 areraised above that level so that the sheets can pass unhindered onto aseries of conveyor bands 41 which are driven by a pulley 42 via a belt21 from a source of motive power partly visible at 43. The undeflectedsheets are transported, as indicated at 30', toward a printing cylinder33 with a form 44 and a cooperating pressure roller 37 which are showndiagrammatically in FIG. 2.

Beyond the rocker arms 16 there is another shaft 20, driven by the belt21, with a set of feed rollers 17, some of these rollers co-operatingwtih counter rollers 18 which are supported by rods 45 on a manuallyrotatable shaft 46. When the arms 16 are swung downwardly (e.g.counterclockwise) under the control of photocells 13, they direct anoncoming sheet into the nip of rollers 17 and 18 which deliver suchsheet to a receptacle 19 as shown at 30". The rocking of the arms 16 isaccomplished by a solenoid 13 which is connected with the rocker shaft15 via a lever 14 and two articulated links 38, 39.

Reference will now be made to FIG. 2 for a description of the circuitryassociated with the photoelectric detector assemblies 1-3 and thesolenoid 13. Each of these assemblies includes a source of light,respectively designated 1a, 2a and 311, as well as an associatedphotocell 1b, 2b and 3b, respectively. Plate 40 is longitudinallyslitted at 1c, 20 and 30 (FIG. 1) to permit light from the lamps 1a, 2a,3a, which may be disposed underneath the plate, to reach the associatedphotocells 1b, 2b, 3b. Photocell 1b is so biased as to remain conductivewhenever light from its lamp 1a reaches it directly or through a singleinterposed paper layer; only in the presence of at least two superposedsheets 30 will the resistance of cell 1b increase sufficiently to applypositive bias to the control grid of a pentode 4 which is connected inparallel with a similar pentode 5 in the operating circuit of a relay 6.Whereas the control grid of tube 4 is tied to the anode of photocell 1b,the corresponding grid of tube 5 is connected to the cathodes of cells2b and 3b in parallel so that the latter tube will conduct whenevereither of these photocells is illuminated by the associated light asource 2a or 3a in the absence of an intervening sheet. The energizingcircuit of light sources 2a and 3a, however, includes a normally openswitch 26 which is closed only periodically under the control of a cam27 synchronized with the printing cylinder 33.

The plate voltage for tubes 4 and is derived from an alternating-currentsource 34 via a transformer 35 and a conventional rectifying network 36.A secondary winding 35a of transformer 35 supplies current to the lamps1a, 2a and 3a.

Also connected across power source 34 are a relay 8 in series with amake contact 7 of relay 6; a solenoid in series with a make contact ofrelay 8; a relay 12 in series with another make contact 11 of relay 8and with a switch contact 22 which is controlled by a cam 23 alsosynchronized with cylinder 33; and the solenoid 13 in series with abreak contact 24 of relay 12. The latter relay further has a holdingcontact 25 and an additional make contact 47 in parallel with contact 9.

A condenser 48, connected across the Winding of relay 6, delays therelease thereof upon the establishment of conduction to either of tubes4 and 5. By a conventional sheet stopper, not shown, the advance of thesheets 30 along the guide path illustrated in FIG. 1 may be regulated sothat a sheet will pass the monitoring assemblies 13 at a time just whenthe cam-controlled switches 22 and 26 are about to close. If only asingle sheet, symmetrically disposed with reference to the detectors1-3, passes the control point, and its lateral edges are substantiallyparallel to the guide rails 31, the photocells 2b and 3b will beshielded from their light sources while the cell 1b will continue toconduct; underthese circumstances, the tubes 4 and 5 remain cut oif andthe relay 6 is not operated. Printing proceeds then in the normalmanner.

If, however, the cell 112 is obscured by the superposition of two ormore sheets, and/or a sheet is positioned obliquely or olf-center sothat one or the other cell 215, 3b will be illuminated, relay 6 willoperate to energize the relay 8 and, via armature 9 of the latter, relay12 which locks over its holding contact 25 in series with cam switch 22and by its break contact 24 de-energizes the normally actuated solenoid13 connected with lever 14. A spring 49 now swings this levercounterclockwise to rock the arms 16 (FIG. 1) into theirsheet-deflecting position. Solenoid 10, initially energized by contact 9of relay 8, is maintained operative by contact 47 of relay 12independently of the state of energization of relays 6 and 8 until thecam 23 has completed its revolution to reopen the switch 22 and torelease the relay 12.

Relay armature 47 could be omitted if condenser 48 is chosen largeenough to maintain the relay 6 energized throughout the portion of anoperating cycle during which the form 44 moves past the roller 37, thisroller being normally urged by a spring 50 against the cylinder 33. Itwill be apparent that smudging of the roller 37, and therefore of asubsequently arriving paper sheet, will not occur as long as the rollerbears only upon the cylinder periphery not occupied by the form 44.

Manually operable switches, not shown, may be provided for the purposeof deactivation of one of the other detector assembly 1 or 2, 3.

We claim:

1. In a printing plant having a form-carrying printing cylinder and aco-operating pressure roller for holding a sheet to be printed againstthe periphery of said cylinder upon rotation of the latter, thecombination therewith of guide means forming a path for sheets to besuccessively fed to said cylinder, photoelectric detector means at saidpath for sensing the position of said sheets and producing a defectsignal in response to an improper positioning thereof, sorting meanscontrolled by said detector means for deflecting improperly positionedsheets from said path in response to said signal, electromagneticrelease means controlled by said detector means for temporarilydisengaging said pressure roller from said cylinder in response to saidsignal, said release means being provided with circuit means formaintaining said roller disengaged from said cylinder, independently ofsaid detector means, for at least a major portion of an operating cycle,and timer means coupled with said cylinder for maintaining said sortingmeans in a sheet-deflecting position for the remainder of an operatingcycle during which said signal is emitted by said detector means.

2. The combination defined in claim 1 wherein said circuit meansincludes relay means, energizing means for said relay means responsiveto said signal, and capacitive means for maintaining said relay meansenergized beyond the duration of said signal.

3. The combination defined in claim 1 wherein said circuit meansincludes contacts controlled by said timer means.

4. The combination defined in claim 1 wherein said detector meanscomprises a pair of edge-scanning assemblies positioned along oppositesides of said path for concurrent triggering by a properly positionedsheet, and switch means controlled by said timer means for renderingsaid assemblies triggerable only during a predetermined portion of anoperating cycle.

5. The combination defined in claim 4 wherein said detector meansfurther comprises a duplication-detecting assembly positionedsubstantially centrally along said path for triggering by a pair ofsuperposed sheets.

References Cited by the Examiner UNITED STATES PATENTS 2,072,235 3/1937Wormser 27l57 2,072,236 3/1937 Wormser 27l57 2,556,895 6/1951 Baker 27l47 2,947,917 8/1960 OBrien 27l57 X 3,026,419 3/1962 Aweida et a1. 27l57X 3,186,708 6/1965 Hinz 27l57 M. HENSON WOOD, JR., Primary Examiner.

ALLEN N. KNOWLES, Examiner,

1. IN A PRINTING PLANT HAVING A FORM-CARRYING PRINTING CYLINDER AND ACO-OPERATING PRESSURE ROLLER FOR HOLDING A SHEET TO BE PRINTED AGAINSTTHE PERIPHERY OF SAID CYLINDER UPON ROTATION OF THE LATTER, THECOMBINATION THEREWITH OF GUIDE MEANS FORMING A PATH FOR SHEETS TO BESUCCESSIVELY FED TO SAID CYLINDER, PHOTOELECTRIC DETECTOR MEANS AT SAIDPATH FOR SENSING THE POSITION OF SAID SHEETS AND PRODUCING A DEFECTSIGNAL IN RESPONSE TO AN IMPROPER POSITIONING THEREOF, SORTING MEANSCONTROLLED BY SAID DETECTOR MEANS FOR DEFLECTING IMPROPERLY POSITIONEDSHEETS FROM SAID PATH IN RESPONSE TO SAID SIGNAL, ELECTROMAGNETICRELEASE MEANS CONTROLLED BY SAID DETECTOR MEANS FOR TEMPORARILYDISENGAGING SAID PRESSURE ROLLER FROM SAID CYLINDER IN RESPONSE TO SAIDSIGNAL, SAID RELEASE MEANS BEING PROVIDED WITH CIRCUIT MEANS FORMAINTAINING SAID ROLLER DISENGAGED FOR AT LEAST A MAJOR PORTION OF ANOPERATING CYCLE, AND FOR AT LEAST A MAJOR PORTION OF AN OPERATING CYCLE,AND TIMER MEANS COUPLED WITH SAID CYLINDER FOR MAINTAINING SAID SORTINGMEANS IN A SHEET-DEFLECTING POSITION FOR THE REMAINDER OF AN OPERATINGCYCLE DURING WHICH SAID SIGNAL IS EMITTED BY SAID DETECTOR MEANS.